1. Field of the Invention
This invention relates generally to video inspection systems which are used to view selected difficult access areas and, more particularly, to such systems which are used to access areas in potentially explosive environments.
2. Prior Art
In the field of video inspection systems, it is desirable to provide maximum protection for a video camera and associated equipment which is placed in difficult access areas. Usually a camera is placed in some sort of casing which protects the camera as it is lowered into a tank or pulled through a pipeline or other enclosure during inspection operations. When the environment within the enclosure is explosive, extreme measures must be taken to isolate the inspection system from the explosive environment.
One such system utilizes a positive pressure displacement method, wherein a camera casing is pressurized with non-flammable gas through a gas line, which is connected to the casing. Electrical energy is provided to a video camera and lighting system within the casing by electrical cables connected through the casing. Such systems are inherently dangerous since the industrial conditions often encountered by video inspections include elements which can damage or cut gas lines and electrical cables. If the gas service is interrupted, leakage could allow flammable gases or fumes into the casing, where arcing of electrical components could cause an explosion. Of course, should external electrical cables become damaged, arcing could occur outside of the casing.